This invention is directed to a bolting system for securing a first weldment including two spaced apart wall members, and a cross member connected to and extending between the wall members, to a second weldment including a wall member adjacent and in contact with one of said first weldment wall members. Still more particularly, this invention is directed to electric mining shovel car body-crawler frame bolted-joint designs.
Electric mining shovels, through field service history, have had difficulty with car body-crawler frame bolted-joint designs. Relative movements between the car body and crawler frame mounting faces have promoted and contributed to premature structural fatigue cracking in the car body shear ledge. The subsequent repair of the car body structure is generally very time and labor consuming.
Current car body-crawler frame bolted-joint designs rely solely on fastener tension to attempt to hold the joint together and to prevent movement within the joint. But slippage at the interface between the car body and the crawler frame still occurs.
This invention provides a bolting system for securing a first weldment including two spaced apart wall members, and a cross member connected to and extending between the wall members, to a second weldment including a wall member adjacent and in face to face contact with one of the first weldment wall members. The bolting system comprises a first plurality of at least two openings in the one of second weldment wall member and the adjacent first weldment wall member, and a second opening in the other of the spaced apart first weldment wall members. The first plurality of openings are larger than the second opening. The bolting system further includes a rod bolt dowel in a tight fit in the first plurality of openings, the rod bolt dowel having an enlarged end which will not pass through the first plurality of openings, and having an opening through its center aligned with the second opening. The bolting system further includes a rod bolt loosely fitted in the rod bolt dowel opening and in the second opening, the rod bolt having a nut on the first end providing an enlargement that will not pass through either the rod bolt dowel opening or the second opening, and a nut releasably secured to the other end of the rod bolt and providing an enlargement that will not pass through either the rod bolt dowel opening or the second opening.
In one embodiment, the first weldment wall member has a top, and wherein the second weldment wall member has a top shear ledge that sits on top of the one first weldment wall member top.
One of the objects of this invention is to provide a reliable car body-crawler frame bolted-joint design which can be easily assembled by field erection crews, and which can be modified, without substantial rework cost, if assembly difficulties should arise. More particularly, one of the objects of this invention is to provide a bolting system including a dowel that can be remachined to provide a desired precision fit. Also, if the dowel or an opening through the car body or crawler frame should wear, new or oversize dowels can be installed to maintain the desired fit. And, if the dowel should fail, the system could continue to serve its intended function, until such time as when repairs can be made by the customer.
Another of the objects of this invention is to provide a bolting system that provides the soundness and security of a doweled interface with a combination bolt and tapered-flanged dowel that can be assembled together, without additional installation tooling.